Union dyeing of cellulose-cellulose ester textile materials with vat dyes



Patented Oct. 3, 1950 UNION DYEING F CELLULOSErOELLULOSE ESTER TEXTILE MATERIALS WITH VAT I DYES George 0. Ward and William T. Haggerty, Jr.,

Cumberland, Md., assignors to Celanese Corporation of America, a corporation of Delaware No Drawing. Application January 6, 1948, Serial No. 804

l I This invention relates to the dyeing of textile materials having a basis of cellulose acetate or other organic acid ester of cellulose and relates more particularly to a novel process for the 'dye ing of said textile materials with vat dyestuffs.

An object of this invention is theprovision of an improved process whereby cellulose acetate or other organic acid ester of cellulose textile materials may be dyed rapidly and in a continuous manner with vat dyestufis.

Another object of this invention is to provide a processfor the dyeing of mixed materials comprising cellulose acetate or other organic acid ester of cellulose textile material and cellulosic textile material whereby both union and crossdyed efiects may be achieved efficiently and economically and without impairing any of the textile properties of the materials being dyed.

Other objects of this invention will appear from the following detailed description.

Although the vat dyestuffs are noted for their fastness properties, the use of said dyestufi's for the dyeing of cellulose acetate or other organic acid ester of. cellulose textile materials has been quite objectionable since said dyestuffs are usually applied in a strongly alkaline vat and the presence of the alkali therein has a pronounced saiaonifylllg action on the cellulose estermaterials. The saponification not only produces a-loss in weight of the cellulose ester materials but deleteriously afiects the luster, strength and the dyeing properties of the materials as well. Various procede ures have been suggested for the dyeing of cellulose acetate or other organic acid ester of cellulose'materials with leuco vats of reduced alkalinity whereby these difiiculties may be avoided but none of these'has proven to be commercially acceptable. For one thing not only do said procedures permit but a very limited range of shades to be dyed satisfactorily but they also involve a drying of the impregnated textile material prior to oxidation, which step substantially decreases the speed of production. Furthermore, where the textile material being dyed is a mixed material comprising cellulose acetate or other organic acid ester of cellulose textile material in admix! tu re with a cellulosic material, such as cotton or regenerated'cellulose, little or no control over the type of dyeing obtained can beexercised'and attempts to produce commercially acceptable union dyeings or acceptable reserved dyeings wherein either the-cellulose acetatemateri'al or the cellulosic material is reserved are not entirely successful. 1 7;. j J We have now found that cellulose acetate or 2 Claims. (Cl. 8-24) 2 other organic acid ester terials may be'dyed satisfactorily with vat dyestuffs rapidly and ina continuous manner by treating said textile materials with an aqueous alkaline solution of an alkali metal salt of a leuco vat dyestuff whose alkalinity is controlled to a pH of 10.5 to 11.5 containing a salt of thiocyanic acid and 20 to 50% by weight of diacetone alco- 1101 at a temperature of at least 40 C., rinsing the treated material directly after immersion and then oxidizing the leuco vat dye alkali metal salt on the wet, rinsed textile material-to the colored form. The dyed textile material thus obtained is then rinsed again, soaped and dried. In addition, we have also found that where the material being dyed is a mixed material consisting of an organic acid ester of cellulose textilematerial and a cellulosic material such as cotton or generated cellulose, very satisfactory I union dyeings may be obtained. Union dyeing may be effected by suitably varying the proportion of the diacetone alcohol employed in the leuco vat dyebath. Thus, under the proper conditions, namely, with a diacetone alcohol concentration of 20 to 35% by weight, we have found that very satisfactory union dyeings may be obtained. -By increasing the proportion of diacetone alcohol in the dyebath to above about 35% by weight, however, cross-dyed effects may be obtained wherein the organic acid ester of cellulose material is dyed and the cellulosic material therein is substantially reserved.

As examples of the salts of thiocyanic acid which may be satisfactorily employed in the leuco vat dyebaths employed in our novel vat dyeing process there may be mentioned sodium thiocyanate, potassium thiocyanate, ammonium thiocyanate, and zinc thiocyanate. The thiocyanic acid salt may be employed in amounts of from 0.5 to 5% based on the weight of the dyebath. As stated, the dyeing is effected with the alkaline leuco vat dyebath at a temperature of at least 40 C. during the dyeing orimpregnating step. Preferably, the temperature should not exceed about C. Satisfactory dyeing is readily achieved by subjecting the material to be dyed to the action of the alkaline leuco vat dyebath for a period of from only 15 seconds to 1 and not more than about 2 minutes, before rinsing and oxidation. -Our novel dyebath, ac-

cordingly, permits exceedingly rapid penetration and dyeing. r

After the textile material has been suitably impregnated with the dyebath the impregnated of cellulose textile maamples are given;

3 textile material is then rinsed directly without any intermediate drying and the leuco vat dyestuff on the wet, rinsed material is then oxidized to the colored form. A suitable oxidizing bath may be employed such as an aqueous solution containing from about 0.1 to'0.5%.'by weightof sodium bichromate and from about 0.3 to 1% by weight of acetic acid employing a temperature of 20 to 40 C. and maintaining the impregnated textile material in the oxidizing. bath for-from 1 to 15 minutes. FOllowing theoxidization, the dyed textile material is preferably rinsed in warm water, soaped and dried. I

The textile materials dyed in accordance with out novel process may be in the form. of yarns, filaments, staple fibers or fabrics and any convenient method of impregnation such "as padding or the like may be employed. a

the pH is maintained at between 10.5 and 11.5.

A cellulose acetate fabric of a satin construction' is placed in the dyebath for 15 seconds with the latter maintained at 47 C., the impregnated fabric removed, rinsed directly and without drying, and the dyestuif on the wet, rinsed fabric then oxidized by immersing the fabric for 10 minutes in a 0.1% by weight solution of sodium bichromate at 30 C. containing 0.3% by weight In order further to illustrate our invention, but

without being limited thereto, the following ex- 1 E l I A dyebath is formed by adding 3 parts by weight of Ponsol Jade Green (ColorIndex Np. 1l01 gto750 parts by Weight of water'containing 2 partsby weight of sodium hydrosulfite and 10 parts by weight of a 10% by weight aqueous solution of'sodium hydroxide, and the dye is vatted in this solution for 15 minutes at 50 C. A solution is formed of 20 parts by weight of sodium thiocyanate dissolved infillO parts by weight of water to which 140 partsby weight of diacetone alcohol are added, and the solution thus obtained is poured into the alkaline solution of the vatted dyestuff. The alkaline 'leuco vat dyebath thus formed contains, in addition to the alkali metal salt of the leuco vat dyestuif, 26.6% by weight of diacetone alcohol, 3.8% by weight of sodium thiocyanate and 68.3% by weight of water as well as the small amount of sodium hydrosulfiteand sodium hydroxide indicated so'that the pH is between 10.5 and 11.5.

A cellulose acetate fabric of a satin construction is placed in the dyebath for one minute with the dyebath maintained at a temperature "of 47 C., the fabric is then removed, rinsed directly and Without drying, and the dyestufi on the wet, rinsed fabric is then oxidized by immersion in a 0.1% by weight solution of sodium bichromate containing 0.3% by weight of acetic acid for 10 minutes maintained at 30 0. Following oxidation, the dyed fabric is then rinsed, soaped and dried. The fabric is dyed a uniform blue green shade. ,The dyebatlrmay also be employed for the union dyeing of a mixed cellulose acetate and viscose fabric. Thus, when a fabric consisting of spun yarns of mixed cellulose acetate and regenerated cellulose staple fibers is dyed in the manner described above and employing said vatdyebath, the mixed fabricis uniondyed and both the cellulose acetate andregenerated cellulose fibers present are evenly dyed in a uniform blue green shade. i

Y Example II 7 I I A dyebath is formedby adding parts by weight of Ponsol Yellow 'GC paste {Color Index No. 1118) to 50 parts by weight of water containing 2 parts by weight of sodium hydrosulfitc and 10 parts by weight of a 10% by weight aqueous solution of sodium hydroxide, and the dye is vatted in this solution for minutes at 50' C. parts by weight of sodium thiocyanateare dissolved in 3G0 parts by weight of water, "140 of acetic acid. The oxidized fabric is then rinsed,

soaped and dried. The fabric is found to be dyed a uniform yellow shade. When a fabric consisting of spun yarns of mixed cellulose acetate and regenerated cellulose staple fibers jis dyed, as 'described above, employing said vat dyebath, the mixed fabric is union dyed and both the cellulose acetate and regenerated cellulose fibers present therein are dyed in a. uniform yellow shade.

The degree of saponification of the cellulose acetate material resultingfrom the use of said alkaline vats is relatively small due'to the short period during which it is necessary to expose the textile material to the action of said alkaline vat to obtain proper penetration. Thus, where the cellulose acetate material, prior to dyeing, has an acetyl value of 54%, calculated as acetic acid, the dyed material is found to have an acetyl value of 53.7% after a 15 second immersion, 53.4% after a 30 second immersion and 52.9% after a 1 minute immersion. This reduction in acetyl value does not effect any noticeable alteration in the textile properties of the material.

While theapplication of the novel vat dyebaths of our invention has been more particularly described in connection with the dyeing of cellulose acetate textilematerials, textile materials having a basis of other organic acid esters of cellulose may similarly be. dyed. Examples of other organic acid esters of cellulose are cellulose propionate, cellulose butyrate, cellulose acetate-propionate and cellulose acetate-butyrate. Cellulose etherv materials having a basis of ethyl cellulose or benzyl cellulose may also be dyed satisfactorily by our novel process. The cellulosic materials which may be dyed by our novel process are, for example, cotton, regenerated cellulose produced by the viscose process and regenerated cellulose obtained by the saponification of organic acid esters of cellulose.

' It is to be understood that the foregoing detailed description is given merely by way of illustration and that many variations may be made therein without departing from the spirit of'our invention. 7

Having described our-invention, what we desire to secure by Letters Patent is:

, 1. Process for the union dyeingof textile materials with vat dyesufis, which comprises treating amixed textile material consisting of'anorganic acid ester of cellulose textile material in admixture with a cellulosic textile material with an aqueous alkaline solution of an alkali metal salt of a leucc vat dyestuff at a pH of 10.5 to.11. 5 containing 05 to 5% by weightofsodium thiocyanate and 20 to 35% by weight of diacetone alcohol at a temperature of 40 to 70C., for 15 seconds to, 2 minutes, rinsingthe treated textile. material directly after treatment, and oxidizing the leuco vat dyestufi on the wet, rinsed textile material.

2. Process for the union dyeing of textile materials with vat dyestuffs, which comprises treating a mixed textile material consisting of a cellulose acetate textile material in admixture with a cellulosic textile material with an aqueous alkaline solution of an alkali metal salt of a leuco vat dyestufi at a pH of 10.5 to 11.5 containing to by weight of diacetone alcohol and 0.5

' to 5% by weight of sodium thiocyanate at a temperature of 40 to C., for 15 seconds to 2 minutes, rinsing the treated textile material directly after treatment, and oxidizing the leuco vat dyestuif on the wet, rinsed textile material.

GEORGE C. WARD. WILLIAM T. HAGGERTY, JR.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

1. PROCESS FOR THE UNION DYEING OF TEXTILE MATERIALS WITH VAT DYESTUFFS, WHICH COMPRISES TREATING A MIXED TEXTILE MATERIAL CONSISTING OF AN ORGANIC ACID ESTER OF CELLULOSE TEXTILE MATERIAL IN ADMIXTURE WITH A CELLULOSIC TEXTILE MATERIAL WITH AN AQUEOUS ALKALINE SOLUTION OF AN ALKALI METAL SALT OF A LEUCO VAT DYESTUFF AT A PH OF 10.5 TO 11.5 CONTAINING 0.5 TO 5% BY WEIGHT OF SODIUM THIOCYANATE AND 20 TO 35% BY WEIGHT OF DIACETONE ALCOHOL AT A TEMPERATURE OF 40 TO 70* C., FOR 15 SECONDS TO 2 MINUTES, RINSING THE TREATED TEXTILE MATERIAL DIRECTLY AFTER TREATMENT, AND OXIDIZING THE LEUCO VAT DYESTUFF ON THE WET, RINSED TEXTILE MATERIAL. 